let action = {
   'jia':function(a,b){
   console.log(a+b);
   },
   'jian':function(a,b){
    console.log(a-b);
   },
   'cheng':function(a,b){
   console.log(a*b);
   },
   'chu':function(a,b){
    console.log(a/b);
   },
  'all':function(a,b){
    this.jia(a,b);
    this.jian(a,b);
    this.cheng(a,b);
    this.chu(a,b);
  }
}
module.exports=action;
